1. Field of the Invention
The present invention relates to a document feeding apparatus and, more particularly, to a document feeding apparatus used in image forming equipment such as a copying machine and an information recording device.
In particular, the present invention relates to a document feeding apparatus for image forming equipment, which has an image area designation function, automatically aligns a document or original on an original exposure table (platen), and exhausts a copied sheet.
A document feeding apparatus and an image area designation device (to be referred to as a digitizer hereinafter) which are used in a copying machine will be exemplified.
2. Related Background Art
In a conventional copying machine, in order to copy an original, an operator places the original on an original table (e.g., platen glass). In copying of a plurality of original sheets, a document feeder has been recently proposed and used in practice to automatically feed original sheets and copy them since it is inconvenient to manually place original sheets on the original table one by one.
FIG. 1 is a sectional view showing a typical example of a conventional automatic sheet document feeder. Referring to FIG. 1, original sheets 2 are stacked on an original feed tray 1. In this case, the upper surfaces (i.e., image surfaces) of the original sheets face down in FIG. 1. A pickup roller 3 is made of a material such as a rubber-based material having a large friction coefficient and swings about a feed roller shaft 10. A feed roller 5 (made of the same material as that of the pickup roller 3) is fixed to the feed roller shaft 10. The feed roller 5 is rotated upon rotation of the feed roller shaft 10. This rotational force is transmitted to the pickup roller 3 through a gear (not shown). The rotational direction of the feed roller 5 is the same as that of the pickup roller 3. At the same time, the peripheral velocity of the feed roller 5 is the same as that of the pickup roller 3. A rotating shaft (not shown) of a first paper feed roller 4 is fixed to the paper feed tray 1. When the original sheet 2 is inserted between the pickup roller 3 and the first paper feed roller 4 and the pickup roller 3 urges the original sheet, the roller 4 is driven.
A second paper feed roller 6 slidably urges the sheet against the roller shaft 10. When the original sheet passes between the feed roller 5 and the second feed roller 6, the second paper feed roller 6 is driven. A pickup arm 8 pivots about a pickup arm shaft 7 as a pivot shaft and has a U-shaped groove 9a at its one end. A shaft 9b fixed to a paper feed arm 9 pivotal about the feed roller shaft 10 as the pivot shaft is fitted in the U-shaped groove 9a of the pickup arm 8. If the pickup arm shaft 7 is pivoted counterclockwise (as viewed), the pickup arm 8 is pivoted counterclockwise and the paper feed arm 9 is also pivoted counterclockwise about the feed roller shaft 10. At this time, the pickup roller 3 is separated from the first paper feed roller 4. If the pickup arm shaft 7 is then pivoted clockwise, the pickup arm 8 is pivoted in the same direction. The paper feed arm 9 is also pivoted clockwise about the feed roller shaft 10. Therefore, the pickup roller 3 having separated from the first paper feed roller 4 is brought into tight contact with the first paper feed roller 4. If an original sheet 2 is present, it is clamped and can be fed between the pickup roller 3 and the first paper feed roller 4.
An original sensor 11 comprises a reflection sensor for detecting the presence/absence of an original sheet. A leading end sensor 12 comprises a reflection sensor for detecting the leading end of the original sheet.
A wide belt 15 comprises an endless belt which has a width covering the entire surface of the original sheet. The belt 15 is covered with a rubber-based material having a high friction coefficient sufficient to feed the original with the friction force. The surface of the coating on the belt 15 is treated such that contamination can be removed therefrom by alcohol or the like. The belt 15 is looped between a driving roller 13 and a turn roller 19. The turn roller 19 is designed such that a shaft 19a is biased to the left in FIG. 1 so as to keep the belt 15 taut and prevent the belt 15 from sliding slid with respect to the driving roller 13. The driving roller 13 has a driving shaft 14. Press rollers 16, 17 and 18 are in rolling contact with the inner surface of the belt 15. Each of the distances between the feed roller 5 and the press roller 16, between the press rollers 16 and 17, between the press rollers 17 and 18, and between the press roller 18 and an exhaust roller 20 is slightly narrower than the size of original sheets which can be fed. The roller 16, 17 and 18 urge the belt 15 with a small pressure against an original platen glass 47 on the copying machine housing. When the original sheet 2 passes between the original platen glass 47 and the belt 15, a feeding force is increased.
The automatic document feeding apparatus also includes an exhaust sensor 22 for detecting exhaustion of a sheet original If the original is not detected within a predetermined period of time, a jam lamp (not shown) is turned on.
Exhaust rollers 20 and 50 are biased by exhaust rollers 21 and 51, respectively. The original sheet is clamped between the exhaust rollers 20 and 21 and between the exhaust rollers 50 and 51 after copying is completed. The original sheet is then discharged on an exhaust tray 61. The exhaust rollers 20 and 50 are rotated by a driving belt 49, and the exhaust rollers 21 and 51 are driven upon feeding of the original sheet. The roller 51 is rotatably mounted on an exhaust roller shaft 51a.
Referring to FIG. 2, a driving gear 42 is fixed on a rotating shaft 43a of a motor 43. A motor rotational force is transmitted from the driving gear 42 to a gear 40 through an idler gear 41. Rotation of the gear 40 is transmitted to a clutch shaft 44 upon on/off operation of an electromagnetic clutch 35. Upon energization of the electromagnetic clutch 35, the rotational force of the gear 40 is transmitted to the clutch shaft 44. An electromagnetic brake 34 stops rotating the clutch shaft 44. Upon energization of the electromagnetic brake 34, the clutch shaft 44 is stopped. A gear 36 is fixed to the clutch shaft 44. When the clutch 44 is rotated, the gear 36 is also rotated to transmit the rotational force to a clock disc gear 37 so that the rotational speed is increased and a clock disc 38 is rotated at the increased rotational speed. The clock disc 38 has many slots on its peripheral portion. The number of grooves is read by a photointerruptor 39. The rotational force of the clutch shaft 44 is transmitted to a driving roller shaft 14 by a belt 32 looped between a driving pulley 33 fixed to the clutch shaft 44 and a driven pulley 31 fixed to the driving roller shaft 14. A pulley (large) 25 is mounted on the driving roller shaft 14 through a spring clutch (not shown). A plunger 27 controls a spring clutch control ring 26 through a clutch ratchet 28, thereby transmitting or stopping transmitting the driving force. A pulley (small) 23 receives a rotational force of the pulley (large) 25 through a belt 24 and is coupled to the feed roller shaft 10 through a one-way clutch (not shown).
The ratio of the diameter of the pulley (large) 25 to that of the pulley (small) 23 is selected such that the peripheral velocity of the belt 15 is slightly faster than that of the feed roller 5. When the original sheet 2 is caught by the belt 15 and is fed at the same speed as that of the belt 15, the pulley (small) 23 is coupled to the roller shaft 10 through the one-way clutch such that the feed roller 5 follows the original sheet 2. It should be noted that the feed roller 5 and the pickup roller 3 are coupled through a gear mechanism such that they have the same rotational direction and the same peripheral velocity. A plunger 30 causes the paper feed roller shaft 9 to pivot through a lever 29, thereby vertically moving the pickup roller 3.
The operation of the automatic document feeder with the above arrangement will be described hereinafter.
The original sheets 2 are placed on the paper feed tray 1 and one original sheet 2 is inserted between the pickup roller 3 and the paper feed roller 4. The original sensor 11 detects the presence of the original sheet 2. When a predetermined period of time has elapsed, the plunger 30 is energized to move the pickup roller 3 downward, thereby causing the pickup roller 3 and the paper feed roller 4 to clamp the original therebetween (when the original sheet is not detected, the pickup roller 3 is kept in the upper position). At the same time, the motor 43 is rotated and the clutch 35 is energized to rotate the driving roller 13. In this state, the plunger 27 is not energized, and the pulley (large) 25 is stopped by a spring clutch (not shown). Therefore, the original sheet is not fed. When a predetermined period of time has elapsed upon rotation of the motor 43, the plunger 30 is energized and the clutch ratchet 28 is separated from the control ring 26. The driving shaft 14 is rotated and its rotational force is transmitted to the feed roller shaft 10 to start rotating the feed roller 5 and the pickup roller 3. In this state, the original sheet 2 starts to be fed. When the distal end of the original sheet 2 passes between the feed roller 5 and the second paper feed roller 6, the distal end of the sheet 2 is detected by the distal end sensor 12. From this timing, the photointerruptor 39 starts counting the clocks of the clock disc 38. The original sheet 2 is inserted between the belt 15 and the original platen glass 47. When the distal end of the original sheet 2 is located below the press roller 16, the feeding force of the belt 15 is increased so that the peripheral velocity of the original sheet 2 is the same as that of the belt 15 and is faster than that of the feed roller 5. The feed roller 5 is driven upon movement of the original sheet 2. When the trailing end of the original sheet 2 is detected by the paper sensor 11, the plunger 30 is deenergized and the pickup roller 3 is moved upward. The trailing end of the original sheet 2 is detected by the distal end sensor 12, and at the same time the plunger 27 is deenergized. The feed roller 5 and the pickup roller 3 are stopped. This is not to accept the next original sheet.
When the distal end of the original sheet is detected by the distal end sensor 12 and the photointerruptor 39 counts the predetermined number of clocks, the motor 43 is deenergized. At the same time, the clutch 35 is deenergized. The brake 34 is then energized to immediately stop the clutch shaft 44. Rotation of the driving shaft 14 and then that of the belt 15 is stopped. The original sheet 2 is stopped at a predetermined position of the original platen glass 47. Energization of the brake 34 is interrupted after the lapse of a predetermined period of time. As soon as the brake 34 is deenergized, a copy start signal is supplied to the copying machine to start copying. The exposure operation of the copying machine is thus started.
The motor 43 starts rotating in response to a copy end signal. The clutch 35 is energized to cause the belt 15 to exhaust the original sheet 2. The original sheet is inserted between the exhaust rollers 20 and 21 and between the exhaust rollers 50 and 51. The original sheet 2 is exhausted onto the exhaust tray 61. When the original sensor 11 detects the presence of the original sheet, the plunger 27 is energized after the exhaust sensor 22 detects the leading end of the original sheet 2. The original sheet is fed in the same procedures as described above.
A driving force of the sheet exhaust section is transmitted from a gear 48 fixed to the turn roller 19 to a gear 46 through an idler gear 45. The gear 46 is fixed to an exhaust roller shaft 20a so that the shaft 20a and the gear 46 are rotated together. A pulley 20b is fixed to the exhaust roller shaft 20a, and the rotational force is transmitted to a pulley 52a fixed to a shaft 52 through a belt 49.
While the belt 15 is being driven, the exhaust rollers 21 and 51 in the original exhaust section receive the driving force.
It should be noted that if an original such as a book is to be copied, the automatic document feeder is opened/closed to place the book on the platen glass 47.
In addition to the automatic document feeder described above, other multifunction devices with new functions are often combined with a copying machine in recent years.
A double copying function is one of the new functions. Different original images are formed on one side of transfer sheet. Assume that one original has an image at a given portion thereof, and that the other original has an image at a portion different from the given portion. The image of one original is formed on a given surface of the transfer sheet and then the image of the other original is then formed thereon, so that the different images are formed on one surface of the transfer sheet, thereby achieving double copying.
Double copying can be performed in a conventional copying machine. After a transfer sheet having an image of one original is exhausted outside the copying machine, the same sheet is fed in the copying machine through a manual feed tray to perform second copying. On the other hand, in a recent conventional copying machine, if a double copying is selected on an operation panel, the transfer sheet is automatically circulated to perform double copying for different originals. Another improved conventional copying machine is also proposed. According to this copying machine, when the operator simply places different originals (e.g., two originals) on the original table, selection of double copying allows automatic double copying even if the original is not manually replaced with the next original.
Another new function is a multicolor copying machine. In this copying machine, a color (e.g., red or blue) developing unit is used in place of the normal black toner developing unit to obtain a multicolor copy. For this purpose, the black toner developing unit is replaced with another color toner developing unit. A plurality of color toner developing units in addition to the black toner developing unit are accommodated in a most advanced existing copying machine. If the operator specifies a desired color on the operation panel, a multicolor image can be automatically obtained.
If the double copying and multicolor copying functions are combined, improved multifunctional features can be designed. In this case, if double copying and multicolor copying functions are selected at the same time, a multicolor image as a combination of images of the different originals is automatically formed on one surface of a single transfer sheet. In addition, the image of one original may be copied in black, the image of other original may be copied in a color different from black, and the black and another color images are formed on the same surface of the single transfer sheet.
Still another function is an image area designation function. According to this function, a necessary image area is extracted from a single original image, and only the extracted image is copied. For this purpose, a desired image area is measured by X and Y values. These values are input at the operation panel The light-emitting array arranged near a photosensitive body for forming an image is locally and time-serially turned on in response to the input signals, and the latent image of the unnecessary area on the photosensitive body is erased, thereby obtaining only the image of the desired area.
In a copying machine with an image area designation function, the image area is designated by using a coordinate detection element (a so-called digitizer). When the operator places an original on a digitizer and depresses the necessary image area, the desired image area is automatically detected. In this case, the above-mentioned measurement need not be performed, resulting in convenience.
If all the double copying, multicolor copying, and image area designation functions are combined, further improved multifunctional features can be designed. If the double copying operation described above is performed, the positions of the images of the originals must be different. For this purpose, the originals having images at different locations must be selected. However, if the area designation function is used together with the double copying function, the image areas which will cause overlapping of images can be erased to widen selection of the types of originals for double copying. Therefore, by combining the three functions, double copying and multicolor imaging can be performed regardless of the types of originals.
FIG. 3 shows a conventional copying machine with a digitizer and a document feeder. The manipulation procedures of the copying machine will be described hereinafter.
The operator places a desired original 112 on a digitizer 101 such that the image surface of the original 112 faces upward, that the right end of the original abuts against an original abutment (not shown), and that the rear side (the lower surface in FIG. 3) of the original 112 abuts against an abutment (not shown). The operator inputs a desired area of the original surface with a stylus pen 113. Various digitizer input and detection schemes have been proposed and a detailed description thereof will be omitted. When the input operation is completed, the operator designates with function keys 114.sub.1, 114.sub.2, . . . and 114.sub.n whether the designated area image is reproduced or whether different colors are designated. In this manner, the operator sets a desired mode or a combination of modes. Signals input at the digitizer 101 and the function keys 114.sub.1 to 114.sub.n are sent to the copying machine housing through a signal lines 115.
Subsequently, the operator places the original 112 at a predetermined position (not shown) on the original feed tray 1 of the document feeder such that the image surface of the original 112 faces downward. The operation of the automatic document feeder has been described above, and its description will not be repeated. By these operations, the operator obtains a desired image, i.e., an image of the designated area, an image of the area excluding the designated area, a colored image of the designated area.
Typical multifunctional features in recent copying machines have been described above. However, copying machines with these functions are not conveniently used yet for the following reason.
In the conventional copying machines of this type, the digitizer is located on a copying machine where copying operation is not interfered, or outside the copying machine. In addition, since the digitizer has a size larger than original sizes which can be copied, the location of the digitizer is limited.
In particular, if the digitizer is located outside the copying machine, the operator must perform many operation procedures.
More specifically, the operator must place the original to allow the original end to abut against the corresponding abutment and this operation is inconvenient. In addition, when an image area designation error occurs, area designation must be performed again from the beginning to result in cumbersome, time-consuming manipulation.